To provide a method for efficiently refining, with less energy consumption, a composition comprising ethanol, 1-butanol, other organic compound(s) and water for the purpose of separating ethanol, 1-butanol and the other components from the composition, to provide a method for efficiently producing 1-butanol from ethanol, and to provide a production system to be used therefor.

The method for refining the composition comprising ethanol, 1-butanol, other organic compound(s) and water (a water-alcohol composition) for the purpose of separating ethanol, 1-butanol and the other components from the composition is provided, comprising refining the ethanol and/or 1-butanol by distillation after undergoing the step of removing water from the composition.